The effect of epsilon-aminocaproic acid (EACA) on the degradation of aqueous pollen extracts was studied by isoelectric focusing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunoblotting. The extracts were stored at 4 degrees C for 7 days and at 37 degrees C for 1, 4, and 7 days. Addition of 0.1 mol/L of EACA before storage partly protected the extract from degradation. The protective effect of EACA could be demonstrated most clearly by immunoblotting, suggesting that more epitopes were preserved in an antigenic configuration. The stabilizing effect increased with higher EACA concentrations.